Two-dimensional x-ray mammography is currently the gold standard for the detection of breast cancer in its early stages. However, a limitation of this modality is that in a two-dimensional projection of the breast superimpositions of normal tissue may look suspicious and lead to false positives while reviewing two-dimensional x-ray mammography images. Moreover, true lesions can be obscured by overlying breast tissue. In order to diminish these problems, usually two views of each breast are acquired for examining the respective breast, i.e. a craniocaudal (CC) view and a mediolateral oblique (MLO) view, wherein the MLO view is acquired at an angle between 30 degrees and 60 degrees from the CC view.
DBT was introduced as a promising modality to overcome these projection problems, wherein DBT includes a reconstruction of a three-dimensional volume of the breast from several low dose, limited angle x-ray projections. With the introduction of DBT it was suggested that by adding the third dimension only one tomosynthesis view per breast would be required. However, recent insights indicate that in DBT also two views may be required, in order to optimally visualize lesions, as disclosed, for instance, in the article “Breast tomosynthesis: one view or two?” by E. A. Rafferty et al., Meeting Radiological Society of North America, page 335 (2006).
If DBT volume images corresponding to different views need to be reviewed for detecting breast cancer, information from both views need to be combined. However, since the DBT volume images comprise many slices, combining information from the different views is very difficult and time consuming for a radiologist.